The Solar System By Megan Zelenka and Sophia Yearoo

INTRODUCTION The Solar System that we live in consists of a giant star, the sun and the nine planets. These planets are: Mercury,Venus,Earth,Mars, Jupiter, Saturn,Uranus, Neptune and Pluto. The solar system orbits the centre of the galaxy which consists of 200 billion stars we call the Milky Way. The three nearest galaxies are called :the Large Magellanic Cloud, the Small Magellanic Cloud and the Andromeda Galaxy. This is 4 times larger than our galaxy and 200 million light years away. These are just a few examples of the billions of known galaxies in the universe.

The nine planets The nine planets of our solar system are: Jupiter, Saturn,Uranus, Neptune, Earth, Venus, Mars, Mercury and Pluto (biggest to smallest). Only one of these planets are inhabited (Earth, by Humans) but there is evidence to show that there may be life on Mars. Mercury, Venus, Earth and Mars are known as the terrestrial planets (they have a hard, rocky surface). Venus, Earth and Mars have a similar atmosphere but Mercury has almost nothing. Jupiter, Saturn, Neptune and Uranus are called Jovian planets because of the gargantuan size. They are also called the Gas Giants (consisting of gas) although all of them have solid cores)

Stars and the Sun. The Stars Every star in the sky is an enormous ball of glowing gas. Stars can live for billions of years. A star is born when an enormous cloud of hydrogen collapses until it is hot enough to burn nuclear fuel (producing a huge amount of heat and radiation). The sun is our nearest star. It provides the Earth,which orbits at a distance of 150 million kilometres,the right amount of light and heat to support life. Solar eclipses. They take place every 18 months, when the moon moves in front of the sun’s disc. Eclipses can be total, where the whole disc is covered, or annular, where the moon is a little farther away and a ring of the sun can still be seen.

Mercury Mercury is the closest planet to the sun. As a result of this, it is so bright that astronomers can see it through their telescopes at night. It is often known as a morning star, because it shines brightest at dawn just before the sun rises. It is also called an evening star, for the same reasons. It is a lot smaller than earth, and does not have a molten core like Venus and Earth. Because of this it has already cooled completely. As the Mercury's iron core cooled, it has shrunk. This caused its rocky crust to become wrinkled. Scientists call these wrinkles Lobate Scarpes. Mercury has no atmosphere because it is so small and has so little gravity. It also has no moons.

Venus Venus is the second planet away from the sun and the sixth largest. Venus is the hottest planet in our solar system and it’s surface is an extremely hostile environment. It’s average temperature is 464°and it’s clouds move at about 350km per hour. Venus’s atmosphere is 96% CO2, 3% nitrogen and 1% trace other gases( water vapour and sulphur dioxide). Venus is named after the Roman goddess of beauty and love.

Saturn Saturn is a planet in the Solar System. It is the 6th planet from the Sun. Saturn is the second largest planet in the Solar System. Like Jupiter, Uranus and Neptune, Saturn is made mostly of gas and does not have a solid surface. Saturn has 61 moons, (plus 3 others that are not confirmed yet as of 2009). The largest moon is Titan, which is larger than the planet Mercury. Also around Saturn there is a very large system of rings, made of ice with smaller amounts of rocks and dust. Saturn is about 1.4 billion km from the Sun. It takes 29.5 Earth years to orbit around the Sun.

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